# Footnotes and References

## Chapter Two

1. From NOAA

2. Other countries operate other constellations of satellites and use a different acronym or term for their systems, such as the Russian GLONASS system, the European Galileo system, and the Chinese BeiDou system

3. The term “trilateration” is often confused with the term “triangulation”. Triangulation assumes that angles are being solved for, but in the case of GNSS, we are looking for distances - the distance between the user/receiver and the satellite - meaning we are solving for distance, thus “trilateration”, not triangluation

4. Nautical miles are derived from a system based upon dividing the Earth into equal parts of latitude and longitude, while statute, or land, miles are derived from a Roman measure of 1000 left foot strikes of the marching Army, a unit called millum passum, or one thousand paces. So, similar names, different strategies to obtain the measurement.

5. Officially decided by vote during the International Meridian Conference in 1884, the Prime Meridian passes through the Royal Observatory, and came from the Airy Transit Circle, a place where 72% of the world’s navigational maps were already using as the 0 point. Prior to 1884 (and massive expansion of communication and railways) maps and time zones were determined by local needs. With this expansion, an international standard needed to be determined.

## Chapter Three

1. Even though attribute tables can be opened in Microsoft Excel, they should only should be with a very specific reason. Tampering with attribute tables outside of a GIS software can permanently damage them.

## Chapter Four

1. The link is also found in the Help menu via the “ArcGIS Resource Center” option. Once the resource center opens, the help menu is found by choosing the Desktop: ArcMap link in the help menu

## Chapter Five

1. Pt = points. In typography, the point is the smallest unit of measure. It is used for measuring font size, leading, and other items on a printed page. ... The DTP point is defined as ​1⁄72 of an international inch (about 0.353 mm) and, as with earlier American point sizes, is considered to be ​1⁄12 of a pica.

## Chapter Six

1. Even though the app may be free to download, a subscription based Enterprise Esri/ArcGIS Online account is needed to collect and analyze data.